The present invention relates to a pager receiver for receiving pager signals having a predetermined baud rate.
The pager receiver intermittently receives the pager signals. Each of the pager signals comprises a preamble signal and one or more batch signals succeeding the preamble signal. Each of the batch signals comprises a synchronization code signal and a plurality of address signals or groups succeeding the synchronization code signal. A particular one of the address signals is assigned to the pager receiver. Each of the address signals comprises a call number signal and a message.
The pager receiver usually uses a battery for an electric power source and includes a receiving circuit for receiving the pager signal. The receiving circuit is supplied with the electric power from the battery.
A battery saving technique is known in the art for strictly restricting the power supply to the receiving circuit from the battery. The receiving circuit has a battery saving switch and is connected to the battery through the battery saving switch. A battery saving signal comprises power-off signals and power-on signals. The battery saving switch is repeatedly turned on at a predetermined time period shorter than the preamble duration. When the preamble signal is detected or when the predetermined baud rate is detected, the power-on signal is kept until the synchronization code signal is detected at first. Then, the battery saving signal becomes power-off signal. Thereafter, the power-on signal is repeatedly produced at timings for receiving the synchronization code signal and the particular address signal in each of the batches.
In order to enhance the power saving, it is desired for the receiving circuit to receive only particular address signals after receiving the first synchronization code signal. However, if the power-on signal for receiving the synchronization code signal is not produced thereafter, stop of the pager signal cannot be detected. Accordingly, the power-on signals are repeatedly produced for receiving the particular address signal even after stop of the pager signal. This makes a problem that the pager receiver erroneously operates by presence of noise or other signals during absence of the pager signals.